Can you strike out by four foul balls?

Answer 1

The batter can foul as often as necessary, unless there are 2 strikes and the batter bunts foul. That becomes a third strike and the batter is out. Also if there are two strikes and the batter foul-tips the ball into the catcher's mitt, that's also strike 3 and the batter is out.

Answer 2

Not in high school or college or MLB. There could be local slowpitch softball leagues that have a rule like that but there is no such rule in Baseball.

Answer 3

Only if 1) the fourth foul is caught in the air, or 2) the fourth foul is bunted foul.